Devices for attaching two objects together, such as are widely used to fasten tags or labels to garments and the like, are disclosed in Bone U.S. Pat. No. 3,444,597 (issued May 20, 1969) and Kirk U.S. Pat. No. 3,380,122 (issued Apr. 30, 1968), both patents being owned by the assignee of the instant application. Such prior art attaching devices or attachments generally comprise an elongated filament-like member having an object-penetrating part at one end thereof, and a part at the other end thereof which is enlarged relative to the thickness or diameter of the elongated member. The object-penetrating part is designed to be passed through a hole (whether pre-existing or made as part of the attaching operation) in the object. The object-penetrating part has a normal axial orientation substantially lateral or transverse to the axis of the elongated member to form a T-shaped configuration therewith, but is resiliently deformable relative to the elongated member so that the axes may be temporarily aligned. The thus aligned object-penetrating part and elongated member are capable of passing end-wise through the aligned hole of the objects with which it is to be associated, but upon release of the deforming force they resume their normal T-shaped configuration. Accordingly, after attachment the object-penetrating part is disposed on the far side of the object, the elongated member passes through the holes, and the enlarged part remains on the near side of the objects; thus escape of the attachment from the objects in question in one direction is precluded by the laterally-extending object-penetrating part, and in the other direction by the enlarged part.
As disclosed in the cited patents, the attachments are generally provided in the form of an assembly or "clip" of a plurality of such attachments -- a typical clip includes 20 attachments. An attaching mechanism or "gun" of the type disclosed in Bone U.S. Pat. No. 3,103,666 (issued Sept. 16, 1963 and owned by the assignee of this application) may be employed to form the hole through the object with which the attachment is to be associated (or the holes through the objects to be fastened together), sever a single attachment from the assembly of attachments, and force the object-penetrating part of the attachment through the hole(s) to the far side. The attachment in question, particularly when used in connection with such an attaching "gun", may be applied quite rapidly even by relatively unskilled personnel, thus greatly reducing the cost of tagging, labeling and securing objects to one another in general.
The aforementioned attachments have become extremely widely used in industry for the attachment of tags and labels to articles to be sold on the retail market as the attachments are particularly effective in preventing unscrupulous shoppers from switching tags -- that is, removing a tag from a low-priced article, attaching it to a higher-priced article, and then paying only the lower price for the higher-priced article. Nevertheless, the fact that both ends of the attachment are exposed raises the possibility that a new scheme might be devised for switching tags from a low-priced to a higher priced article. For example, an unscrupulous shopper given sufficient time might be able to align the normally transverse axes of the elongated member and the object-penetrating part, then thread the two back through the holes of the object and tag, and thereafter make any desired substitution. Accordingly, an attaching device of the type described in Francis G. Merser et al. U.S. Pat. application Ser. No. 467,918 entitled "Interlocking Attachment Device" (filed concurrently herewith and owned by the assignee of the instant application) was devised to provide a self-contained attachment wherein the parts at the ends of the elongated member were interlocked during attachment. In such an attachment the enlarged part is formed with a hollow interior adapted to receive and retain the object-penetrating part; more particularly, the hollow enlarged part is formed with a sidewall defining a hollow interior, an end wall having an aperture therethrough leading into the hollow interior and an imperforate end wall opposed to the apertured end wall and connected thereto by the sidewall. In this manner, once the object-penetrating part was inserted into the hollow interior the only way the attachment could be removed from an object would be by actual breaking of the elongated member, thereby preventing its subsequent use and providing a clear indication of tampering. An additional advantage of such a self-contained, interlocking attachment is that it simultaneously functions as means for hanging articles for display.
While the self-contained, interlocking attachment has been found to perform successfully, manufacture of the attachment has so far required the molding of at least two distinct pieces -- the elongated member, the object-penetrating part and the sidewall and apertured end wall portions of the hollow enlarged part as a first piece, and the imperforate end wall of the hollow enlarged part as a second piece -- and the subsequent joining of the two pieces by adhesive techniques. Construction of the various parts of the attachment, and in particular the hollow enlarged part, in situ is precluded by the well recognized limitations of the molding art as regards the formation of hollow tubular parts with specific interior and exterior configurations and two end walls providing but a single aperture of limited diameter leading into the interior; at best the two pieces could be formed in a single molding operation with a flexible hinge or connecting member therebetween to prevent loss of either piece during handling by the manufacturer. Attempts at a one piece construction of the attachment, involving the molding only of the first piece and heat sealing of the exposed edges of the sidewall of the hollow enlarged part to form in situ an imperforate end wall, were not entirely satisfactory for the same reason that heat sealing of the second piece (i.e., the distinct imperforate end wall) onto the first piece was not a recommended manufacturing technique. Despite the simplicity and economy of a heat sealing operation (whether of a single or two piece construction), various problems which precluded commercial utilization of heat sealing in the manufacture of attachments were encountered. The heat produced at the seal area during the operation affected through heat conduction other areas of the hollow enlarged part. More particulaly the thermoplastic material defining the aperture of the apertured end wall and the hollow interior formed by the sidewall could deform to such a degree that portions of the deformed material would block passage of the object-penetrating part through the apertures and/or into the hollow interior. Heat deformation of the exterior surface of the sidewall not only resulted in an aesthetically unappealing appearance for the hollow enlarged part, but also tended to weaken the connection of the elongated member to the sidewall exterior surface.
Accordingly, it is an object of the present invention to provide a self-contained, interlocking attachment wherein the object-penetrating part is secured within a unitary hollow enlarged part to preclude tampering therewith, the hollow enlarged part being unitarily formed of thermoplastic material in a single molding operation and completed by heat sealing of one end of the part.
It is another object to provide such an attachment in which one end of the hollow enlarged part is formed by heat sealing without deleteriously affecting to any appreciable degree the remainder of the part.
An object of the present invention is to provide a self-contained, interlocking attachment which can be maufactured by means of simple, inexpensive molding nd heat-sealing operations.